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Search: id:A054419
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| A054419 |
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Number of connected 3 X n binary matrices (divided by 2). |
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+0
2
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| 3, 21, 143, 953, 6347, 42285, 281719, 1876913, 12504659, 83310469, 555043871, 3697898985, 24636713627, 164138517789, 1093548978567, 7285610864737, 48539321706403, 323386164243445, 2154513238908591, 14354130788161817
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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A connected (0,1) matrix is one where you can get from any black square, i.e. 1, to any other by chess king moves.
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REFERENCES
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R. Levy and J. Shapiro, Uniqueness in paint-by-numbers puzzles, preprint, 2000.
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FORMULA
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a(n)=7a(n-1)-3a(n-2)+5a(n-3).
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CROSSREFS
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Cf. A054417-A054421.
Number of connected 3 X n binary matrices = 2*A054419 = 4*A054417 + 2*A054418.
Sequence in context: A141041 A079753 A137969 this_sequence A033888 A141492 A088088
Adjacent sequences: A054416 A054417 A054418 this_sequence A054420 A054421 A054422
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), May 22 2000
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EXTENSIONS
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More terms from James A. Sellers (sellersj(AT)math.psu.edu), May 23 2000
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